command_buffer: Implement glGetStringi for GL ES 3.0

gpu/command_buffer/build_gles2_cmd_buffer.py

Index: gpu/command_buffer/build_gles2_cmd_buffer.py
diff --git a/gpu/command_buffer/build_gles2_cmd_buffer.py b/gpu/command_buffer/build_gles2_cmd_buffer.py
index 8cd382f85b86d0213d2b0ebf6a3de34ed2669d22..c855043f0e8c5a79e0e8895764d914562cc852ee 100755
--- a/gpu/command_buffer/build_gles2_cmd_buffer.py
+++ b/gpu/command_buffer/build_gles2_cmd_buffer.py
@@ -1452,6 +1452,14 @@ _NAMED_TYPE_INFO = {
       'GL_EXTENSIONS',
     ],
   },
+  'IndexedStringType': {
+    'type': 'GLenum',
+    'is_complete': True,
+    'valid': [
+      'GL_EXTENSIONS',
+    ],
+  },
+
   'TextureParameter': {
     'type': 'GLenum',
     'valid': [
@@ -3233,6 +3241,12 @@ _FUNCTION_INFO = {
     'client_test': False,
     'cmd_args': 'GLenumStringType name, uint32_t bucket_id',
   },
+  'GetStringi': {
+    'type': 'Custom',
+    'client_test': False,
+    'gen_cmd': False,
+    'unsafe': True,
+  },
   'GetSynciv': {
     'type': 'GETn',
     'cmd_args': 'GLuint sync, GLenumSyncParameter pname, void* values',